I don't know if you can install Mac os x & Windows on the same RAID 0, since as far as I know, Macs create RAIDs using software (but I'm not sure)
I've no experience in creating RAID 0 in mac os x. Try this one - http://macs.about.com/od/usingyourmac/ss/raidstripe_2.htm
With windows 7, its pretty simple.
Your motherboard manual will have instructions regarding setting RAID 0. Just follow them to the letter.
If at all this does seem like a bother, just forget about the RAID 0 & install the OSes on two different drives ...